Oracle 19c is the long-term support release of the Oracle Database family, offering: - Extended support until April 2027 (with optional 2030) Extended support until April 2027 (with optional 2030) - Automatic indexing , JSON support , and better performance tuning features Automatic indexing , JSON support , and better performance tuning features - Improved stability , security , and high availability Improved stability , security , and high availability - Compatibility with Oracle Cloud Infrastructure (OCI) Compatibility with Oracle Cloud Infrastructure (OCI) If you’re still on Oracle 12c , upgrading to 19c ensures long-term support and modern capabilities.

Traditional upgrade methods (like DBUA , Data Pump , or RMAN restore ) often require downtime during migration — which can be several hours or even days. Oracle GoldenGate eliminates this downtime by: - Capturing changes from the source (12c) in real-time Capturing changes from the source (12c) in real-time - Delivering them to the target (19c) continuously Delivering them to the target (19c) continuously - Allowing a seamless cutover when both databases are fully synchronized Allowing a seamless cutover when both databases are fully synchronized ✅ Result: Continuous application availability with Zero Downtime .

Here’s the high-level flow: GoldenGate continuously captures and applies committed transactions from the source to the target, maintaining synchronization throughout the process.

- Install Oracle 19c on a new server (target environment). Install Oracle 19c on a new server (target environment). - Ensure network connectivity between the 12c and 19c servers. Ensure network connectivity between the 12c and 19c servers. - Set up Oracle GoldenGate binaries on both systems (same GoldenGate version). Set up Oracle GoldenGate binaries on both systems (same GoldenGate version).

- Verify that both databases use supported character sets . Verify that both databases use supported character sets . - Ensure supplemental logging is enabled on the source: Ensure supplemental logging is enabled on the source: - Confirm that primary keys exist on all replicated tables. Confirm that primary keys exist on all replicated tables.

Create dedicated users for GoldenGate replication on both databases: Add GoldenGate privileges as per Oracle documentation.

On the source (12c) : Start the extract process:

On the target (19c) : Start the replicat process:

Perform an initial load using: - Oracle Data Pump ( / ) Oracle Data Pump ( / ) - or GoldenGate initial load utility or GoldenGate initial load utility Once the initial data is loaded, GoldenGate ensures ongoing synchronization by applying all captured changes from 12c to 19c.

- Verify lag time between extract and replicat using: Verify lag time between extract and replicat using: - Compare record counts or perform checksum validation between source and target databases. Compare record counts or perform checksum validation between source and target databases.

When both databases are in sync: - Stop the application briefly (just seconds/minutes). Stop the application briefly (just seconds/minutes). - Stop extract and replicat processes. Stop extract and replicat processes. - Redirect applications to the 19c target database. Redirect applications to the 19c target database. - Start the application — now running on Oracle 19c! Start the application — now running on Oracle 19c! ⏱️ Total downtime: A few seconds to minutes (for switchover only).

Using GoldenGate isn’t just about the upgrade; it provides strategic advantages: - Rollback Plan: If something goes wrong during cutover, you can instantly switch back to the 12c database, as it has been kept in sync. Rollback Plan: If something goes wrong during cutover, you can instantly switch back to the 12c database, as it has been kept in sync. - Load Balancing: You can offload reporting and batch jobs to the 19c database before the cutover. Load Balancing: You can offload reporting and batch jobs to the 19c database before the cutover. - Future-Proofing: You now have a tested and operational real-time data replication tool for future migrations, disaster recovery, or active-active setups. Future-Proofing: You now have a tested and operational real-time data replication tool for future migrations, disaster recovery, or active-active setups.